1. Field of the Invention
The present invention relates to a methodin connection with a measuring device detecting hydrometeors.
2. Description of Background Art
The invention also relates to an apparatus used in connection with a sensor detecting hydrometeors.
The method to which the invention relates concerns, sensors that measure precipitation is its various forms (especially water, snow, and hail), and which are based on detecting the mechanical impulses created when hydrometeors strike the detector surface. The method is suitable for both sensors, which measure the hydrometeors striking the detector surface directly, and sensors equipped with a funnel-like collector, which measure the water exiting as drops from the collector. The information provided by the sensor can be the amount of precipitation, the intensity of precipitation, the type of precipitation, the kinetic energy of the precipitation, or some other quantity that can be calculated from the impulses created by hydrometeors.
A sensor and method detecting hydrometeors that directly strike a detector surface are disclosed in, for example, a previous patent application by the applicant (Finnish application number 20011876). A precipitation sensor operating on a similar principle is also disclosed in EP publication 0 422 553 B1 and in German patent application DE 44 34 432 A1. A version equipped with a collector is disclosed in a previous application by the applicant (Finnish application number 20011875).
The sensors described in the above applications have certain drawbacks, which limit their use. The first relates to the power consumption of the sensors. Precipitation is typically measured in places, in which mains electricity is not readily available. Therefore, in the case of an electrical measuring device, dry-cell or accumulator batteries, or a battery-solar-cell combination are generally used as the power supply, so that, from the point of view of the apparatus's manufacturing and operating costs, power consumption should be substantially minimized. The sensors described in the above publications are formed from a sensing element and the related electronics, which amplifies the sensor signal and performs the signal processing necessary to generate the output signal. Through the sensing element as such can be passive, (for example, a piezoelectric element), the measuring electronics are switched on the whole time waiting for possible drops of precipitation and consuming power. Thus the solutions disclosed above are not optimal in terms of power consumption.
Another drawback of the known solutions is the disturbances caused by mechanical impacts and vibration due to other factors than hydrometeors striking the detector surface. Vibrations transmitted from the environment through the support structures of the sensor, or caused by the wind, if they are sufficiently strong, can cause triggering in the detection circuit, leading to a mechanical disturbance being registered spuriously as a hydrometeor.